What does it mean?
P1701 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: MIL Request Circuit Malfunction (4L30-E) .
Symptoms
- Warning lamp stays on permanently, or never illuminates during the key-on bulb check
- Transmission may still shift normally, so lamp behaviour is the only visible sign
- Other transmission codes are stored but the lamp does not respond to them
- Emissions inspection failure because of incorrect lamp operation
- Lamp flicker that follows road vibration
- Communication codes stored alongside in either module
Likely causes
- Open, shorted or high-resistance wire on the lamp request circuit between the transmission module and the engine module
- Corroded or backed-out terminals at either module connector
- Chafed harness section grounding the request line against the body or a bracket
- Failed output driver inside the transmission module
- Poor ground shared by both modules
- Water intrusion into the transmission module connector
- Faulty input circuit in the engine module for the request signal
How to fix it
- Verify lamp operation at key-on: it should light for the bulb check and go out once the engine is running
- Identify the request circuit in the wiring diagram and check it for continuity end to end
- Measure the circuit for shorts to ground and to battery positive with both modules disconnected
- Inspect and clean both connectors, looking for spread, corroded or pushed-out pins
- Voltage drop test the grounds for both modules under load
- Repair the damaged wire with a soldered and sealed joint, then secure it clear of chafe points
- Replace the transmission module only after the request circuit and grounds are proven good